The long range purpose of this project is to determine the reason why the Drugs of Abuse are used. The study inquires of users of a given drug what alteration takes place when he is taking the drug. Early in our studies, we learned that chronic users of marijuana refused to take it when in groups in which they could carry on a good conversation. Their reason for this was unclear. More recently, we have found that information learned under marijuana is better remembered when again under marijuana than when straight and vice versa. This year we have shown that marijuana enhances the right hemisphere's ability to process information.